Method for preparing colloidal dispersions



Oct. 30, 1962 T. w. MARTINEK 3,061,544

METHOD FOR PREPARING CQLLOIDAL DISPERSIONS Original Filed Oct. 6, 1954 2Sheets-Sheet l 9 HEN DISPERSION EXCHANGE/7 V r a f a a F I6. I

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7 INVENTOR.

THOMAS W. MA RT/NEK BYFMWA7 ATTORNEY Oct. 30, 1962 1-. w. MARTINEKMETHOD FOR PREPARING COLLOIDAL DISPERSIONS 2 Sheets-Sheet 2 OriginalFiled Oct. 6, 1954 FIG. 3

HOT GONGENTRA TE INLE T INVENTOR. OUTLET THOMAS W. MARTINEK 5M ATTORNEY3,061,544 METHOD FOR PREPARING COLLOlDAL DISPERSIONS Thomas W. Martinek,Crystal Lake, 11]., assignor to The Pure Oil Company, Chicago, 11]., acorporation of Ohio Original application Oct. 6, 1954, Ser. No. 460,653,new Patent No. 2,905,448, dated Sept. 22, 1959. Divided and thisapplication Aug. 29, 1958, Ser. No. 753,013

11 Claims. (Cl. 252-32) The invention relates to a method for preparingcolloidal dispersions, exemplified by lubricating grease com positionsin which the method is characterized by simultaneous lowering of thetemperature, pressure, and concentration during shearing and Working ina single zone.

According to the prior art it is conventional to pulverize solids, as,mineral material, by providing two or more currents or streams of aliquid which are discharged under high pressure past an orificeconveying the solids into contact with the streams. Devices are inexistence wherein a solid is conveyed through a venturi-type arrangementand through rotational means wherein it picks up a liquid or impingesupon a liquid stream rotating in the opposite direction. Converginghigh-pressure jets are used to disperse particles of liquid or solids byimpingement on a target which may be rotating. Various closely spacedorifices between rotors and stators are used to crush or disperseparticles in gaseous or liquid media. In the grease-making art, it isconventional to heat a preformed soap or gel and an organic liquidcarrier, as, a mineral lubricating oil, while mixing or working themixture. The resulting grease is allowed to cool statically until theproper gel structure is formed and then the gel is subjected to milling,diluting, or homogenization processes to form the finished product. Inall of these applications wherein a solid is comminuted by itself or ina gaseous or liquid medium it is not always possible to regulate thenature or extent of comminuation or dispersion attained by controllingall of the phase changes simultaneously and the advantages of one typeof operation, for example, the use of a high-pressure jet, are unrelatedto the attainment of closely controlled dispersion. Prior art methods donot provide simple, inexpensive, flexible, and readily adaptabletechniques for continuous production of dispersions. In the Votatormethod of grease making, a continuous stream of all the ingredients ispassed through a high-temperature heat exchanger to effect the formationor solution or both of the solid phase in the liquid phase throughelevation of temperature. The resulting solution is then cooled atpredetermined rates to effect a colloidal dispersion of the solid phaseat a lower temperature. These operations are followed by homogenizationto effect greater dispersion of the solid phase. Excessive amounts ofheat and rigid control of the processing conditions are necessary inthese prior art processes and there is little flexibility in technique.In some instances, it is desirable to form dispersions which are verydifficult, or even impossible, to stabilize with existing equipment. Thepresent invention is directed to a method designed to overcome these andrelated shortcomings of the prior art.

Accordingly, a primary object of this invention is to provide a methodfor preparing emulsoidal dispersions and emulsions of a solid phase orphases in one or more liquid phases.

A second object of the invention is to provide a process for preparingemulsions or emulsoidal dispersions wherein simultaneous lowering oftemperature, pressure, and concentration during working is accomplished.

A third object of the invention is to provide a method wherein a liquidphase is contacted at high velocity with a solid phase undersimultaneous cooling, pressure lower- 3,0fil544 Patented Oct. 30, 1962IQQ ing, and concentration change during extreme shearing or working.

Other objects and advantages of the invention will be apparent from thefollowing description.

Although the invention relates to the preparation of dispersions of asolid phase in a liquid phase generally, it will be described inrelation to grease manufacture as an illustrative process. Greasesrepresent a particularly sensitive type of dispersion or gel structureand the state of aggregation of the gel has a very marked effect on thephysical properties of the grease as related to water resistance,resistance to bleeding, dropping point, and the like.

For a better understanding of the invention, reference is made to theaccompanying drawings, wherein:

FIGURE 1 is a general flow diagram illustrating the relationship ofauxiliary apparatus used to carry out the invention in the preparationof emulsoidal dispersions and emulsions using the specifically designeddispersion means to be described in detail in the subsequent figures.

FIGURE 2 is a cross-sectional view of one form of dispersion headassembly.

FIGURE 3 is a sectional view taken along lines 33 of FIGURE 2.

FIGURE 4 is a partial cross-sectional view of another form of dispersionhead assembly.

In accordance with the invention, the preparation of dispersions orgreases is facilitated by dissolving the colloid-forming or solid phasein a minimum amount of the colloid-bearing or liquid phase by applyingsufiicient heat to produce a solution which is called the hot,concentrated solution. This hot, concentrated solution is injected underhigh pressure through jet or spray nozzles into a zone of lower pressureand lower temperature where the jets or sprays meet or impinge againstthe balance of the liquid phase, also injected under high pressure. Theeffect of this rapid temperature-drop, rapid pressure-drop on the hot,concentrated solution with simultaneous concentration change, and thecombined high velocity, thin-stream or spray injection into a rapidlymoving, comparatively cool, liquid phase creates an extremely finecolloidal dispersion of the solid phase in the liquid phase. Completeand accurate control of temperature, pressure, and concentration ismaintained on both the hot, concentrated solution and the balance of theliquid phase.

In order to better understand the invention, reference Will first bemade to the general flow diagram of the process which will beillustrated by its application to the manufacture of lubricatinggreases. Following this, specific embodiments and structures of theapparatus will be described.

Referring to FIGURE 1, about one-third of the total lubricating oil ischarged to kettle 1 along with the soap stocks. Kettle '1 may comprise astandard Dopp kettle equipped with an agitator 2 and suitable heatingmeans (not shown) in order to raise the temperature of the concentrateto about to 185 F., preferably about 180 F. At this point a watersolution of a metal base, as lithium hydroxide, is added with agitation.The temperatureis raised to 275 F. to 285 F., preferably about 280 F.,as the hot concentrate loses water. When dehydration is substantiallycomplete, any oxidation inhibitors or other addends intended to beincorporated in the grease are added and uniformly dispersed. Next, thebatch is pumped through line 4 by variable-speed, posifive-displacementpump 3 into line 5 controlled by valve '6 (by-pass line 7 controlled byvalve 8 being closed), and thence into heat exchanger 9 wherein thetemperature is brought to about 380 F.

From heat exchanger 9 the hot solution passes through line 10 controlledby valve 11 into dispersion unit 12.

The details of the different embodiments of dispersion unit 12 will beexplained in connection with FIGURES 2, 3, and 4. As the hot,concentrated solution passes through the dispersion area of unit 12, thebalance of the remaining, comparatively cold oil (about /3 of the totaloil) is being pumped into line 13 by another variable-speed,positive-displacement pump 14. Back-pressures of approximately 400 and500 p.s.i.g. are maintained on inlet lines and 13 respectively. Thepumping rates of the two pumps are adjusted to give the proper ratio ofhot solution to cool diluting oil. The final product leaves thedispersion unit 12 via dispersion unit outlet 15 for immediatepackaging.

Referring now to FIGURE 2, one arrangement of dispersion unit is shownin cross-section wherein housing forms an enclosure or dispersion area21 and receives plate 22 by threaded engagement as at 23. Plate 22 has aplurality of openings, 24, 25 and 26 through which pass conduits 27, 28and 29, respectively. Conduits 27, 28 and 29 are threaded on their outersurfaces to receive lock nuts 30 and 31 (at the top) 32, 33(intermediate) 34 and 35 (bottom) which draw against gaskets 36, 37(top) 38, 39 (intermediate) 40 and 41 (bottom) to form a liquid-tightseal around the conduits adjacent to the openings. The threaded end ofeach conduit Within the dispersion area 21 of housing 20 protrudessufiiciently to receive opposing outer jet nozzles 42, 43 and 44 inthreaded engagement as shown at 45, 46 and 47. Jet nozzles 42, 43 and 44are fitted with constricted tips 48, 49, 50 and 51 which are threadedwithin the jet nozzles as indicated at 52, 53, 54 and 55. Housing 20 hasan aperture 56 into which is fixed exit line 57 to convey the finisheddispersion to immediate packaging.

Conduits 27 and 29 preferably convey the cool diluting oil, and conduit28 conveys the hot concentrate. Thus, referring to FIGURE 1, conduits 27and 29 would be connected to line 13 of FIGURE 1 and conduit 28 wouldcommunicate with line 10 of FIGURE 1 in connecting the dispersion unitshown in FIGURE 2 therewith. Jet nozzle tips 48 and 49 have theiropenings directly opposite each other so that their respective dischargestreams meet head-on for maximum dispersion. The same is true of tips 50and 51. Aperture 58 in nozzle 43 leads to a third tip, not shown inFIGURE 2. A fourth tip connected to an aperture similar to aperture 58is also provided as shown in FIGURE 3.

FIGURE 3 is a sectional view taken along lines 33 of FIGURE 2 showingthe relative position of the outer jet nozzles 42 and 44 with centerbank of nozzles 43. In this view are also shown additional outer jetnozzles 59 and 60 with corresponding tips 61 and 62 in opposed positionto additional center bank nozzles 63 and 64 leading from center banknozzle 43. Outer jet nozzles not shown in FIGURE 2 are here similarlyconstructed and fixed within plate 22 as with lock nuts 65 and 66. It isseen in FIGURE 3 that the hot concentrate emanating from nozzle 43 infour directions is met with cold diluent as a surrounding deluge.

Referring to FIGURE 4, still another form of dispersion unit is shown inpartial cross-section. This form of dispersion unit is a modifiedcolloid mill of the Charlotte type. Case hollow-body or stator 70, hasinlet conduit 71 fitting thereto and has a plurality of ports or slots72 passing through its conical-shaped, internal wall 73. The internalspace 74 of stator conveys the concentrate phase from conduit 71 andforces the concentrate phase under high pressure through ports 72. Ports72 are preferably located near the apex of conical internal wall 73. Theexternal peripheral edge of stator 70 is threaded as at 75 to receivering 76 which has internal thread 77 to engage support ring 78. Ring 78carries bearing 79 and shaft 80. A liquid seal around bearing 79 isprovided by gasket 81 held in place by lock nut 82. Shaft carriesconical rotor 83 held upon the shaft by washer 84 and lock nut 85engaging the threaded portion of the shaft end. Rotor '83 is keyed orotherwise affixed to shaft 80 so that rotation of the shaft by a powersource (not shown) causes rotation of the rotor. The conical outersurface of rotor 83 is parallel to and spaced from the external conicalsurface of wall 73 of stator 70 by a distance of about 2 to 50 thousandsof an inch. This clearance is made adjustable by displacement of shaft80 towards or away from stator 70. The rotating speeds used will varyfrom about 3600 to 7200 rpm.

Depending upon the physical and/or chemical properties of the dispersantand dispersed phase, ports 72 may vary in size from about 0.025 to 0.005inch. The relative size of the ports is a function of the pressure andvelocity, and the viscosity of the dispersed phase. The outer face ofrotor 83 presents a machined surface except for spaced, conicallyarranged grooves shown at 86, 87 and 88. The grooves are equally spacedand concentrically arranged around the periphery of rotor 83 and in theembodiment shown in FIGURE 4, four grooves are present. It is understoodthat any number of grooves may be used on rotor 83.

Ring 76 has port 89 into which conduit 90 is attached. The centerportion of stator 70 has threaded inlet 91 which surrounds and is spacedfrom lock nut 85. Conduit 92 attaches to inlet 91 by threadedengagement.

In order to illustrate the invention which is broadly applicable to thepreparation of dispersions of a solid phase and a liquid phase, themanufacture of a lithium base grease will be used as an example. Toillustrate a grease composition, the following formulation is prepared:Lithium soaps of 60% hydrogenated castor oil- 40% hydrogenated tallow,4.5% by weight; 550 vis. hydrocarbon oil 95%; and oxidation inhibitor0.5%.

This grease composition is processed as follows: A

. hot concentrate is prepared by forming the soaps at a concentration of11.25 percent by weight, in approximate- 1y /3 of the total oil to beused, by the addition of the mixture of hydrogenated castor oil andhydrogenated tallow to the hydrocarbon oil followed by the addition of alithium base such as lithium oxide or lithium hydroxride. This mixtureis dehydrated at a temperature of about 280 F. The hot concentrate isprepared in soap kettle 1 (FIGURE 1) and pumped through lines 4 and 5 tohigh-temperature heat exchanger (9) where the soaps are brought intosolution at approximately 380 F. The resulting hot soap solution is thenready for ejection into dispersion unit 12 via line 10. A backpressureof approximately 400 to 500 p.s.i.g. is maintained on line 10. If unit12 takes the form shown in FIGURE 2, the hot concentrate passes throughconduit 28 into nozzle 43 and out the plurality of jets 49, 50 and 63and 64 (FIGURE 3). The remaining oil /3 of the total) is passed at about500-1000 p.s.i.g. or more through line 13 into dispersion unit 12, orreferring to FIGURE 2, through conduits 27 and 29 into nozzles 42 and 44and jets 48 and 51. In the dispersion unit shown in FIGURE 2, thestreams of hot concentrate from conduit 28 and diluting oil from conduit27 are jetted against each other in opposing streams by the proximityand alignment of the openings therein. These streams are ejected at highvelocities of about 1000 to 4000 feet per second. The resultant greasewhich attains a temperature of 200 F. passes through conduit 57 forimmediate packaging.

The grease exhibits an ASTM worked penetration of about 320 and showspractically no change upon further working. The dropping point of thegrease is about 365 F.

The manufacture of a polyethylene grease comprises another process towhich the apparatus and technique of the present invention isapplicable. Such a grease comprises about 5 percent by weight ofpolyethylene, molecular weight 20,000, dispersed in 95 percent by weightof neutral mineral oil having a viscosity of about 200 SUS at F.Referring to FIGURE 1, about one-half of the neutral oil is charged tokettle 1 and heat and agitation applied. The polyethylene is next addedto form a slurry which becomes a solution at 200-250" F., depending onthe rate of heat application. The solution is pumped through line 7(by-passing heat exchanger 9) into line 10 and dispersion unit 12 withvalves 6 and 11 closed. Meanwhile, the balance of the oil is pumpedthrough line 16 to the dispersion unit 12. The hot concentrate ofpolyethylene enters line 28 (FIGURE 2) at approximately 230 F. and aback-pressure of about 400 p.s.i.g. The oil enters through conduits 27and 29 into nozzles 42 and 44 and other associated conduits (not shown)into nozzles 59 and 60 (FIGURE 3) at a temperature of about 80 F and a400 p.s.i.g. back-pressure. The pumping rates of the pumps handling theconcentrate and diluent oil are adjusted to give the proper ratios ofingredients. The two liquids meet or collide in high velocity streamswhereby instantaneous controlled changes in temperature, pressure andconcentration occur. The hot solution of polyethylene concentrate iscooled, diluted and worked instantaneously. The resulting grease is avery light colored, No. 1 consistency-grade grease with a dropping pointof about 185 F.

Referring to FIGURE 4, the hot concentrate enters via line 71 and fillschamber 74 passing therefrom under high pressure (400 p.s.i.g.) throughapertures 72. The cool diluent oil at about 80 F. enters the dispersionunit via line 92 passes up through the grooves 86, 87 and 88 to contact,dilute and cool the incoming concentrate under the tremendous shearingaction of the rotor 83. Here again simultaneous cooling, dilution andworking take place and a light colored, No. 1 consistency grease isformed.

Numerous other soaps and polymers can be used to make greases by thepresent method. Any soap, polymer, or other material which exhibitsemulsoidal characteristics or which exhibits emulsion-forming tendencieswith a particular liquid may be used with that particular liquid to formcolloidal dispersions or emulsions as the case may be. Thus the processmay be used for making not only many greases but also such compositionsas cosmetics, medicinal salves, ointments, salad dressings, etc. Soapswhich may be used include all the metal soaps of the fatty acids.Polymers which may be used are any of those exhibiting a limitedsolubility in a particular liquid, such as polyacrylates, polystyrenes,etc. in mineral oils. Temperature, pressure and concentration must beadjusted to suit the particular system or type of dispersion desired.

From the description so far given of the invention it is seen that theprocess eliminates the necessity of two cooling steps, one beforedilution and other after dilution as generally considered essential inthe prior art. Another advantage is that the finished product producedby the present method may be passed directly to packaging from thedispersion unit without passing through a rotator or mill. In addition,the method eliminates the necessity of recycling portions of theconcentrate or slurry through a separate shearing operation beforedilution. Also, the necessity of quick quenching in conjunction withsubsequent shearing, previously thought to be advantageous, need nolonger be practiced. Considerable loss in energy and the utilization ofextra equipment is necessary to prepare dispersions according to priorart methods requiring separate cooling and shearing, or quenching andshearing, :along with recycle of a cool stream of finished product asthe quenching medium. The essential feature of rapid heating of thegelling agent or solid phase to solution temperature followed by rapidcooling, characteristic of some prior art processes, is no longernecessary by the practice of the present invention. Consequently, thetemperature to which the slurry or concentrate is heated as comparedwith the temperature of the diluted and worked mixture need not bematters of critical concern since they are subject to direct and easycontrol by the present process. Likewise, the pressuredrop experiencedin the system is within the control of the operator without the need forrecycle pumps or plug valves in the system.

The invention has been described by reference to certain preferredembodiments but it is to be understood that these are not to beinterpreted as limitations on the scope thereof. Certain changes of thefunction of the parts may be made without departing from the spirit ofthe invention. For example, in FIGURE 2 the functions of central conduit28 and outer conduits 27 and 29 may be reversed, that is, the former mayconvey the cool diluent and the latter may convey the hot concentrate.The same is true in FIGURE 4 wherein the cooled diluent may enter theapparatus via conduit 71 and the hot concentrate through conduit 92.

This application is a division of application, Serial No. 460,653, filedOctober 6, 1954, by the instant inventor, now US. Patent No. 2,905,448.

What is claimed is:

1. The process for the preparation of emulsoidal dispersions from asolid phase which is dispersible in a liquid phase at an elevatedtemperature and not dispersible therein at a lower temperature whichcomprises heating a portion of said liquid phase with said solid phaseto form a hot concentrate phase at a temperature higher than saidelevated dispersion temperature and subjecting said hot concentrate tosimultaneous cooling, dilution, shearing and expansion by injection ofsaid hot concentrate, under a pressure of about 400 to 500 p.s.i.g.,into and against a cool stream of the balance of said liquid phase in anexpansion zone and separating said emulsoidal dispersion in stable format a temperature below said elevated temperature without the necessityof milling.

2. The process for the preparation of greases from a gelling agent ofthe group consisting of metal soaps and polymers having a limitedsolubility in a liquid oleaginous phase which comprises heating aportion of said liquid oleaginous phase with said gelling agent to forma hot concentrate phase at a solubilizing temperature, subjecting saidhot concentrate phase to simultaneous cooling, dilution, shearing andexpansion by injection of said hot concentrate at a pressure of about400 to 500 p.s.i.g. into and against a cool stream of the balance ofsaid liquid oleaginous phase in an expansion zone and separating astable grease therefrom.

3. The process in accordance with claim 2 in which the temperature ofsaid hot concentrate phase is about 270 to 380 F. and said liquidoleaginous phase is at a temperature of about F.

4. The process in accordance with claim 2 in which said gelling agent isa metal soap.

5. The process in accordance with claim 2 in which said gelling agent isa polymer having a limited solubility in said liquid oleaginous phase.

6. The process in accordance with claim 4 in which said metal soap is alithium soap.

7. The process in accordance with claim 6 in which said polymer ispolyethylene.

8. The process for the pheparation of greases from a gelling agentselected from the group consisting of metal soaps and polymers having alimited solubility in a liquid oleaginous phase which comprises heatinga portion of said liquid oleaginous phase with said gelling agent toform a hot concentrate phase at a solubilizing temperature, subjectingsaid hot concentrate to simultaneous cooling, dilution, shearing andexpansion by injection of said hot concentrate and the balance of saidliquid oleaginous phase into an expansion zone under conditions wherebyboth of said streams are subjected to co-mingled centrifugal shearingaction at a rotating velocity of about 3600 to 7200 rpm. and backpressures of 400 to 500 p.s.i.g. to form a stable grease without thenecessity of milling.

9. The process for making grease comprising heating a concentrate of aportion of mineral lubricating oil and soap stock to a temperature ofabout 175 to 185 F., adding to said concentrate an aqueous solution of ametal base, heating the resulting mixture to a temperature of about 275to 285 F. for a sufiicient time to dehydrate said mixture, furtherraising the temperature of said dehydrated mixture to about 380 F.,injecting said heated dehydrated mixture as a stream into direct contactwith a stream of cold mineral oil maintained under a back-pres sure ofabout 400 to 500 pounds per square inch whereby said grease mixture issubjected to simultaneous cooling, working, dilution and expansion andthereafter imediately packaging said grease.

10. The process in accordance with claim 9 in which the metal base islithium oxide and said soap stock comprises a mixture comprising about60 percent hydrogenated castor oil and about 40 percent hydrogenatedtallow.

11. The process in accordance with claim 9 in which the hot concentrateis formed from about one-third of the total oil to be used in aconcentration containing about 11.25 percent of a soap stock.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES The Manufacture and Application of Lubricating Greases,Boner, Reinhold Pub. Corp., N.Y., 1954, page 454.

Emulsion Technology, Chem. Pub. Co., Inc., N.Y., 1946, p. 95.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,061,544 October 30, 1962.

Thomas W. Martinek It is hereby certified that error appears in theabove numbered patant requiring correction and that the said LettersPatent should read as corrected below.

Column 6, 1ine-58, for the claim reference numeral "6" read line 60 for"pheparation" read preparation Signed and sealed this 23rd day of April1963.

(SEKLI Anew ERNST w. SWIDER DAVID L LADD Ancsfing officer Commissionerof Patents

1. THE PROCESS FOR THE PREPARATION OF EMULSOIDAL DIS PERSIONS FROM ASOLID PHASE WHICH IS DISPERSIBLE IN A LIQUID PHASE AT AN ELEVATEDTEMPERATURE AND NOT DISPERSIBLE THEREIN AT A LOWER TEMPERATURE WHICHCOMPRISES HEATING A PORTION OF SAID LIQUID PHASE WITH SAID SOLID PHASETO FORM A HOT CONCENTRATE PHASE AT A TEMPERATURE HIGHTER THAN SAIDELEVATED DISPERSION TEMPERATURE AND SUBJECTING SAID HOT CONCENTRATE TOSIMULTANEOUS COOLING, DILUTION, SHEARING AND EXPANSION BY INJECTIONS OFSAID HOT CONCENTRATE, UNDER A PRESSURE OF ABOUT 400 TO 500 P.S.I.G.,INTO AND AGAINST A COOL STREAM OF THE BALANCE OF SAID LIQUID PHASE IN ANEXPANSION ZONE AND SEPARATING SAID EMULSOIDAL DISPERSION IN STABLE FORMAT A TEMPERATURE BELOW SAID ELEVATED TEMPERSTURE WITHOUT THE NECESSITYOF MILLING.